make the gem tx path MPSAFE.

this mostly follows the pattern in ifq.h

ok jmatthew@

diff --git a/sys/dev/ic/gem.c b/sys/dev/ic/gem.c
index 9c5fd6a..c1c34e6 100644 (file)
--- a/sys/dev/ic/gem.c
+++ b/sys/dev/ic/gem.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: gem.c,v 1.121 2017/01/22 10:17:38 dlg Exp $   */
+/*     $OpenBSD: gem.c,v 1.122 2017/06/08 01:34:00 dlg Exp $   */
 /*     $NetBSD: gem.c,v 1.1 2001/09/16 00:11:43 eeh Exp $ */
 
 /*
@@ -75,7 +75,7 @@ struct cfdriver gem_cd = {
        NULL, "gem", DV_IFNET
 };
 
-void           gem_start(struct ifnet *);
+void           gem_start(struct ifqueue *);
 void           gem_stop(struct ifnet *, int);
 int            gem_ioctl(struct ifnet *, u_long, caddr_t);
 void           gem_tick(void *);
@@ -217,9 +217,9 @@ gem_config(struct gem_softc *sc)
        /* Initialize ifnet structure. */
        strlcpy(ifp->if_xname, sc->sc_dev.dv_xname, sizeof ifp->if_xname);
        ifp->if_softc = sc;
-       ifp->if_flags =
-           IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST;
-       ifp->if_start = gem_start;
+       ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST;
+       ifp->if_xflags = IFXF_MPSAFE;
+       ifp->if_qstart = gem_start;
        ifp->if_ioctl = gem_ioctl;
        ifp->if_watchdog = gem_watchdog;
        IFQ_SET_MAXLEN(&ifp->if_snd, GEM_NTXDESC - 1);
@@ -542,6 +542,7 @@ gem_stop(struct ifnet *ifp, int softonly)
        }
 
        intr_barrier(sc->sc_ih);
+       ifq_barrier(&ifp->if_snd);
 
        KASSERT((ifp->if_flags & IFF_RUNNING) == 0);
 
@@ -1625,12 +1626,12 @@ gem_tint(struct gem_softc *sc, u_int32_t status)
 {
        struct ifnet *ifp = &sc->sc_arpcom.ac_if;
        struct gem_sxd *sd;
-       u_int32_t cons, hwcons;
-       u_int32_t used, free = 0;
+       u_int32_t cons, prod;
+       int free = 0;
 
-       hwcons = status >> 19;
+       prod = status >> 19;
        cons = sc->sc_tx_cons;
-       while (cons != hwcons) {
+       while (cons != prod) {
                sd = &sc->sc_txd[cons];
                if (sd->sd_mbuf != NULL) {
                        bus_dmamap_sync(sc->sc_dmatag, sd->sd_map, 0,
@@ -1639,25 +1640,23 @@ gem_tint(struct gem_softc *sc, u_int32_t status)
                        m_freem(sd->sd_mbuf);
                        sd->sd_mbuf = NULL;
                }
-               free++;
-               if (++cons == GEM_NTXDESC)
-                       cons = 0;
+
+               free = 1;
+
+               cons++;
+               cons &= GEM_NTXDESC - 1;
        }
 
+       if (free == 0)
+               return (0);
+
        sc->sc_tx_cons = cons;
-       used = atomic_sub_int_nv(&sc->sc_tx_cnt, free);
 
-       if (used == 0)
+       if (sc->sc_tx_prod == cons)
                ifp->if_timer = 0;
 
-       if (ifq_is_oactive(&ifp->if_snd) && (used + GEM_NTXSEGS <
-           GEM_NTXDESC - 2)) {
-               ifq_clr_oactive(&ifp->if_snd);
-
-               KERNEL_LOCK();
-               gem_start(ifp);
-               KERNEL_UNLOCK();
-       }
+       if (ifq_is_oactive(&ifp->if_snd))
+               ifq_restart(&ifp->if_snd);
 
        return (1);
 }
@@ -1687,35 +1686,43 @@ gem_load_mbuf(struct gem_softc *sc, struct gem_sxd *sd, struct mbuf *m)
 }
 
 void
-gem_start(struct ifnet *ifp)
+gem_start(struct ifqueue *ifq)
 {
+       struct ifnet *ifp = ifq->ifq_if;
        struct gem_softc *sc = ifp->if_softc;
        struct gem_sxd *sd;
        struct mbuf *m;
-       u_int64_t flags;
+       uint64_t flags, nflags;
        bus_dmamap_t map;
-       u_int32_t prod, first, last, i;
-       unsigned int used, new;
-
-       if (!(ifp->if_flags & IFF_RUNNING) || ifq_is_oactive(&ifp->if_snd))
-               return;
+       uint32_t prod;
+       uint32_t free, used = 0;
+       uint32_t first, last;
+       int i;
 
        prod = sc->sc_tx_prod;
-       used = sc->sc_tx_cnt;
-       new = 0;
+
+       /* figure out space */
+       free = sc->sc_tx_cons;
+       if (free <= prod)
+               free += GEM_NTXDESC;
+       free -= prod;
+
+       bus_dmamap_sync(sc->sc_dmatag, sc->sc_cddmamap,
+           0, sizeof(struct gem_desc) * GEM_NTXDESC,
+           BUS_DMASYNC_PREWRITE);
 
        for (;;) {
-               if (used + new + GEM_NTXSEGS > (GEM_NTXDESC - 2)) {
+               if (used + GEM_NTXSEGS + 1 > free) {
                        ifq_set_oactive(&ifp->if_snd);
                        break;
                }
 
-               IFQ_DEQUEUE(&ifp->if_snd, m);
+               m = ifq_dequeue(ifq);
                if (m == NULL)
                        break;
 
                first = prod;
-               sd = &sc->sc_txd[prod];
+               sd = &sc->sc_txd[first];
                map = sd->sd_map;
 
                if (gem_load_mbuf(sc, sd, m)) {
@@ -1732,35 +1739,37 @@ gem_start(struct ifnet *ifp)
                bus_dmamap_sync(sc->sc_dmatag, map, 0, map->dm_mapsize,
                    BUS_DMASYNC_PREWRITE);
 
+               nflags = GEM_TD_START_OF_PACKET;
                for (i = 0; i < map->dm_nsegs; i++) {
+                       flags = nflags |
+                           (map->dm_segs[i].ds_len & GEM_TD_BUFSIZE);
+
                        GEM_DMA_WRITE(sc, &sc->sc_txdescs[prod].gd_addr,
                            map->dm_segs[i].ds_addr);
-                       flags = map->dm_segs[i].ds_len & GEM_TD_BUFSIZE;
-                       if (i == 0)
-                               flags |= GEM_TD_START_OF_PACKET;
-                       if (i == (map->dm_nsegs - 1))
-                               flags |= GEM_TD_END_OF_PACKET;
                        GEM_DMA_WRITE(sc, &sc->sc_txdescs[prod].gd_flags,
                            flags);
-                       bus_dmamap_sync(sc->sc_dmatag, sc->sc_cddmamap,
-                           GEM_CDTXOFF(prod), sizeof(struct gem_desc),
-                           BUS_DMASYNC_PREWRITE);
 
                        last = prod;
-                       if (++prod == GEM_NTXDESC)
-                               prod = 0;
+                       prod++;
+                       prod &= GEM_NTXDESC - 1;
+
+                       nflags = 0;
                }
+               GEM_DMA_WRITE(sc, &sc->sc_txdescs[last].gd_flags,
+                   GEM_TD_END_OF_PACKET | flags);
 
-               new += map->dm_nsegs;
+               used += map->dm_nsegs;
                sc->sc_txd[last].sd_mbuf = m;
                sc->sc_txd[first].sd_map = sc->sc_txd[last].sd_map;
                sc->sc_txd[last].sd_map = map;
        }
 
-       if (new == 0)
-               return;
+       bus_dmamap_sync(sc->sc_dmatag, sc->sc_cddmamap,
+           0, sizeof(struct gem_desc) * GEM_NTXDESC,
+           BUS_DMASYNC_POSTWRITE);
 
-       atomic_add_int(&sc->sc_tx_cnt, new);
+       if (used == 0)
+               return;
 
        /* Commit. */
        sc->sc_tx_prod = prod;